Electrical impulse transmitter



Oct. 14, 1952 w. T. WEIDENMAN 2,613,552

ELECTRICAL IMPULSE TRANSMITTER Filed July 28, 1950 INVENTOR 9 WILLIAM T WEIDENMAN Patented Oct. 14, 1952 ELECTRICAL IMPULSE TRANSMITTER William T. Weidenman, Spring Valley, N. Y., as-

signor to Telephonics Corporation, Huntington, N. Y., a corporation of New York Application July '28, 1950, Serial No. 176,327

This invention relates to electrical impulse transmitters, and has particular reference to calling dials for automatic telephone systems or other apparatus controllable remotely by selective electrical impulses. v

Telephone'calling dials are well known and their construction and operation has become substantially standardized. An incident to their operation is'thefamiliar clicking noise caused by the'dropping of the finger wheel pawl to the bottom of the teeth of the ratchet before the return spring rotates the ratchet wheel through the angle equal to the number of teeth corresponding to the digit dialed, causing the contacts to close an'equal number of times to send that number of electrical impulses. Although this clicking is'not loud, it is distracting and often disturbing, especially where the dial is in almost continual operation as by a telephone operator. Many expedients have been employed to elimi nate or at least deaden the click, but they have either been ineffective or have impaired the efiiciency of operation of the dial in time.

In accordance with the present invention, a simple and inexpensive means is provided for virtually eliminating the clicking noise incident to the operation of the ratchet and pawl mechanism of a calling dial type of impulse sender, without impairing the efficiency of the dial even after extended use, and without requiring attention or replacement of parts other than that normally required in any event.

The. invention comprises an electric impulse transmitterhaving the usual ratchet wheel and pivoted pawl, which is rotated by the finger wheel'oridial in a rearward direction until releasedso that the pawl engages a tooth to rotate the 1 ratchet wheel, the ratchet wheel being grooved peripherally to at least the root circle of the' t'eeth, and a wire spring having. one end anchored on the pawl plate and the free end sliding in said groove intervenes between the pawla'nd' the teeth'so as to deaden the impact thereof.

Intthe' preferred embodiment of the invention, the wirespring has one end anchored in the pivot pin of the pawl to serve as the means for holding the pawl on the pin, and the other end extending in the direction of the pawl and tracking in the ratchet wheel groove, the curvature of the spring being such that it arches slightly above the root circle of the pawl teeth so as to intervene between the pawl and back face of the tooth and thus deaden the impact of the pawl.

In a modification of the invention, the spring 12 Claims. (cite-57s) is" anchored on the pawl plate near the hook of the pawl and the free end of'the springextends past the pawl hook and seats in the'r'atch'et groove between its anchor and the pivot of the pawl so' as to intervene-between the pawl and the ratchet teethat the point of usual impact and'thus deaden the same.

It will be seen that the invention provides a verysimple and inexpensive means for correcting the principal objection to impulse transmitters of the calling dial type, and that the invention may be applied to'existing designs of dials without impairing their efliciency or introducing an element of future 'difficulty.

For a more complete understanding of the invention, reference may be had to the accompany ing drawings, in which:

Figure 1 illustrates a front view of a telephone type calling dial embodying the invention, a por' tionpf certain of the parts being cut away in the'interest' of clarity;

Fig. 2 is an enlarged view of the pawl mechanism of the calling dial illustrated in Fig. 1;

Fig. 3 is an enlarged transverse section through the pawl and ratchet mechanism, as seen along the line'3-'-3 'of Fig. 2; and

:Fig. 4 illustrates a modified form of the invention';

Referring to Fig. 1, numeral 5 designates the finger wheel dial arranged with its finger holes above the number plate 6, and having a central opening keyed to a raised hub portion 8 of the plate 9 and to which it is held by means of a screw threaded in the hole in the center of hub 8. Hence, clockwise manual rotation of the finger wheel 5 results in the movement of plate 9 up to the point where the finger engages stop 1, whereupon the wheel 5 is released and is rotated counterclockwise by a tension spring attached to shaft 15 at a speed controlled by the usual governor, not shown. This return movement of dial 5 and plate 9 is limited by the engagement of a projection on plate 9 with the stop I3.

Pawl I0 is pivoted at H to the plate 9 and is normally urged against and between the teeth I? of ratchet wheel M by the coiled tension spring l2. As the finger wheel 5 is rotated in the clockwise direction, carrying the plate 9 and pawl 10 with'it, the ratchet'wheel M remains stationary and the pawl l0 snaps over the ends and'between the ratchet wheel teeth ll. Upon the return movement of the finger wheel 5 the pawlengages one of the teeth 11, thereby carrying the ratchet wheel l4 along with it and also rotating the gear I6 formed integrally with the ratchet wheel and adapted to operate the impulsing mechanism, not shown. The mechanism just described is conventional and Well known.

Ordinarily, as the pawl I8 drops down into the notches between the teeth I! on the ratchet I4, the familiar clicking noise ensues, owing to the metal-to-metal contact. In order to deaden and thus substantially eliminate this clicking noise, a wire cushioning spring is provided between the pawl and the ratchet teeth. This cushioning spring is designated I8 and is formed of'spring steel wire, Phosphor bronze wire, beryllium bronze wire, or other suitable resilient material capable of withstanding countless operations of the dial without losing its resiliency or breaking.

One end of the cushioning spring I8 is anchored on stationary pin II mounted on pawl plate 9 and on Which the pawl I is pivoted as described. Conveniently-the heel of thepawl I II is bifurcated by a saw-cut slot I9 and the pin II. is drilled radially of the dial at a point within pawl slot I9,so that the reversely turned end 28 of spring-I8 may be inserted into the hole in the pin I I by wayof the access afiorded by the pawl slot I9. The spring I8 thus serves the. secondary purpose of holding the pawl I0 onthe" pin I I without requiring other holding means, and alsoholds itself on thepin II by reason of its springiness, which requires that the loop of the spring be bent to admit the pin II between its end 28 and the main portion of the spring I8, and consequentlythe end 28 snaps into the holein the-pin II when aligned therewith.

The free end of the spring. is turned upwardly and acts as ashoe tracking in a peripheral groove23 out radially through the ratchet wheel I4 toa depth slightly below the 'rootcircle :of the teeth I I, as shown in Figs. 2-and 3. The spring I8 is arched outwardly in a radial direction, so that its arch or bight 22 normally lies -just above the faces of the ratchet teeth II,"as shown in Fig. 2.

In operation of the dial of this invention, the pawl plate '9 rotates with the finger wheel and carries the pawl I8 so that when the dial is turned in the direction of the arrow, the pawl I0 drags over the ends of the teeth I! to normally strike against the faces thereof and make the objectionable clicking noise. However, the arch or bight'22 of the spring I8 intervenes and precludes the pawl ID from striking the face of the corresponding ratchet tooth I! and thus dea'dens the sound, so that the dial equipped with the cushioningspring- I8 is virtually noiseless.

The resiliency of the spring I8 causes it to recoil somewhat upon impact of the pawl I0 therewith, but not enough to allow the pawl ID to strike the face of the ratchet tooth II. It will be'observed that the spring I8, being anchored at one end on pin II, rotates with the pawl plate S-relatively to the ratchet wheel I4 when dialing in the direction of the arrow, so that the shoe 2| of the-spring I 8 is pushed ahead of the pawl III in the groove 23 of the ratchet wheel without any deteriorating torsion by the pawl- I 0 since it is anchored independently of the pawl on stationary pin II. Accordingly, the-spring I8 is relatively stationary with respect to the movements of the pawl I0 except for the slight relative creeping of the shoe 2| as the spring I8 slightly flexes in response to the impact of the pawl ID, of which the spring I8 is otherwise independent and with which it is unconnected.

A modified form of the invention is illustrated in Fig. 4, which is a view similar to Fig. 2 and shows the cushioning spring I 8', anchored on pin 24 secured to pawl plate 9. However, spring I8 extends in the opposite direction from the spring I8 of Fig. 2, in that the spring I8 extends past the pawl hook and seats in the ratchet wheel groove 23 at a point between anchor pin 24 and the pivot II of the pawl, so that when the pawl plate 9 is rotated in the direction of the arrow in Fig. 4, the shoe end 2 I of the spring I8 is dragged in the groove 23 instead of being pushed along therein ahead of the pawl II] as in the case of Fig. 2.

In operation of the modified form of Fig. 4, the arch or bight 22' of cushioning spring I8 intervenes between the pawl I8 and the face of the corresponding ratchet tooth I'Itocushion the-pawl impact and to deaden the soundin the same manner described in connection with Fig. 2. In fact, an axialsection through Fig-:4 similar to that taken along line '3-3 of Fig. 2 would be identical to Fig. 3.

Although certain preferred embodiments'of the invention have been illustrated and adescribed herein, it is to be-understood that the invention is not limited thereby, but is susceptible of changes in form and detail within the scope of the appended-claims.

I claim:

l. In an electrical impulse transmitter having aratchet wheel provided with teeth'aroundits periphery, a, pivoted pawl adapted'to engage-the toothed periphery of said ratchet wheel, and means for rotating said pawl-rearwardly over said ratchet wheel teeth and then to engage a tooth thereof tomove'thei'atchet wheel with the pawl, the combination of a membercarried by said. pawl rotating means-and moving therewith, and cushioning means'mountedon said member and interposed between saidpawl and the bottoms of the notches of said"ratchet-wheel in radially overlapping relation to the-amateurfaces of the ratchet wheel teeth and the notches between them, whereby said cushioning means intervenesbetween' the pawl and the'bottom of a corresponding notch of the ratchet wheel upon impact by the pawl' to thereby 'deaden the impact sound.

2. Inan electrical impulse transmitter having a'ratchet Wheel provided with teeth'around'its periphery,'a pivoted pawl' adapted to'engage: the toothed periphery of said 'ratchetwheelpand means for rotating said pawl rearwardly over said ratchet wheel teeth and then to' engagexa tooth thereof to move the ratchet wheelwith the pawl, the combination of a resilient member interposed between said teeth and said pawl and continuously engaging said means and wheel in radially overlapping relation to the axial surfaces of the ratchet wheel teeth and the notches between them, and means anchoring said member to said means, whereby the member is moved with saidpawl relatively to said wheelduring operation and intervenes between the pawl and the bottom of a notch of the ratchet wheel upon impact by the pawl to thereby deaden the impact sound.

3.-In an electrical impulse transmitter having a ratchet wheel provided with teeth around its periphery, a pivoted pawl adapted toiengagelthe toothed periphery of said ratchet wheel, "and means for rotating said pawl rearwardly over said ratchet wheel teeth and then to engage a tooth thereof to move the ratchetwheel with the pawl, the combination, of a spring wire member interposed between said teeth and said pawl and continuously engaging said means and wheel inradially overlapping relation to the axial surfaces of the ratchet wheel teeth and the notches between them, and means anchoring said ,memb'er to said means, whereby the member ismoved with said pawl relativelyto said ,wheel during operation and intervenes between the pawl and the bottom of a notch of the ratchet wheel upon impact by the pawl to thereby deaden the impact sound.

4. In an electrical impulse transmitter having -a-ratchet wheel provided with teeth around its periphery, a pivoted pawl adapted to engage the toothed periphery of said ratchet wheel, and :nieans for rotating said pawl rearwardly over said ratchet wheel teeth and then to engage a tooth thereof to move the ratchet wheel with the pawl,

the combination of a resilient member having an war'chedportion interposed between said teeth and {said pawl and continuously engaging said means and wheel in radially overlapping relation to the axial surfaces of the ratchet wheel teeth and the wnotches between them, and means anchoring said member to said means, whereby the member is :moved with said pawl relatively to said wheel durving operation and intervenes between the pawl and the botton of a notch of the ratchet wheel upon impact by the pawl to thereby deaden the impact sound. 8 v 5. In an electrical impulse transmitter having of the notches between said teeth and relieving the other end of said member, whereby the mem- "bar is interposed between the pawl and said teeth to thereby deaden the impact sound.

6. In an electrical impulse transmitter having 1a ratchet wheel provided with teeth around its periphery, a pivoted pawl adapted to engage the toothed periphery of said ratchet wheel, and

means for rotating said pawl rearwardly over said ratchet wheel teeth and then to engage a vf. tooth thereof to move the ratchet wheel with the pawl, the combination of a spring wire member carried by said means a one end for movement therewith, said ratchet wheel having a peripheral groove extending radially inwardly through the teeth thereof to at least the bottoms of the notches between said teeth and relieving the other end of said member, whereby the member is interposed between the pawl and said teeth to thereby deaden the impact sound.

7. In an electrical impulse transmitter having a ratchet wheel provided with teeth around its periphery, a pivoted pawl adapted to engage the toothed periphery of said ratchet wheel, and

' means for rotating said pawl rearwardly over said ratchet wheel teeth and then to engage a tooth thereof to move the ratchet wheel with the pawl, -said ratchet wheel having a peripheral groove extending radially inwardly through the teeth thereof to at least the bottoms of'the notches'between said teeth, and a resilient member carried by said means and sliding in said groove and having a portion intervening between said pawl and said teeth for receiving the impact of said pawl and thereby deaden the impact sound.

8. In an electrical impulse transmitter having a ratchet wheel provided with teeth around its periphery, a pivoted pawl adapted to engage the toothed periphery of said ratchet wheel, and means for rotatin said pawl rearwardly over said ratchet wheel teeth and then to engage a tooth thereof to move'the ratchet wheel with the pawl, said ratchet wheel having a peripheral groove extending radially inwardly through the teeth thereof to at least the bottoms of the notches between said teeth,and a spring wire member carried by said means and sliding in said groove and having a portion intervening between said pawl and said teeth for receiving the impact of said pawl and thereby deaden the impact sound.

9. In an electrical impulse transmitter having a ratchet wheel provided with teeth around its periphery, a pivoted pawl adapted to engage the toothed periphery of said ratchet wheel, and means for rotating said pawl rearwardly over said ratchet wheel teeth and then to engage a tooth thereof to move the ratchet wheel with the pawl, said ratchet wheel having a peripheral groove extending radially inwardly through the teeth thereof to at least the bottoms of the notches between said teeth, and a, resilient member carried by said means at one end and sliding in said groove at its other end and having a portion intervening between said pawl and said teeth for receiving the impact of said pawl and thereby deaden the impact sound.

10. In an electrical impulse transmitter having a ratchet wheel provided with teeth around its periphery, a pivoted pawl adapted to engage the toothed periphery of said ratchet wheel, and means for rotating said pawl rearwardly over said ratchet wheel teeth and then to engage tooth thereof to move the ratchet wheel with the pawl, said ratchet wheel having a peripheral groove extending radially inwardly through the teeth thereof to at least the bottoms of the notches between said teeth, and a spring wire member carried by said means at one end and sliding in said groove at its other end and having a portion intervening between said pawl and said teeth for receiving the impact of said pawl and thereby deaden the impact sound.

11. In an electrical impulse transmitter having a ratchet wheel provided with teeth around its periphery, a pivoted pawl adapted to engage the toothed periphery of said ratchet wheel, and means for rotating said pawl rearwardly over said ratchet wheel teeth and then to engage a tooth thereof to move the ratchet wheel with the pawl, the combination of a pivot for said pawl mounted on said means, said ratchet wheel having a peripheral groove extending radially inwardly through the teeth thereof to at least the bottoms of the notches between said teeth, and an elongated resilient member anchored a one end on said pawl pivot and sliding in said groove at its other end and interposed between said pawl and said teeth so as to receive the impact of said pawl and thereby deaden the impact sound.

12. In an electrical impulse transmitter having a ratchet wheel provided with teeth around its periphery, a pivoted pawl adapted to engage the toothed periphery of said ratchet wheel, and

8 REFERENCES CITED The following references are of record in the fiieof't'hispatent:

Number Number 89,498

'VUNITEDISTIATES PATENTS Name Date Grosclaude Nov. '26, 1878 Josleyn 'Feb. 1,-1921 Obergfe11 Oct. 8, 1940 Stenhammer -Nov.'27,-194'5 FOREIGN PATENTS 7 Country Date Germany Man 8, 16, 

